The Michiganisms page is dead on, and even refers to my ancestral home by name (check out "Up North"). I'd add in the following, a verbal "period" frequently used in central and northern Michigan: "I know that." It's the equivalent of "at a minimum," or "for certain."

"He had 16-gauge ammo in stock last week, I know that.""She's full of it--I was there at five o'clock, I know that."